Angiogenesis and aberrant cellular redox state are the hallmarks of the pathogenesis of idiopathic pulmonary fibrosis (IPF), but the mechanisms underlying these pathologic alterations are poorly understood. Failure to understand and target such critical mechanisms directly limits the effectiveness of the therapeutic efforts against this disease. The long-term goal of this study is to develop an effective therapeutic strategy against pulmonary fibrosis and is directly relevant to the mission of National Heart, Lung and Blood Institute. The overall objective of this proposal is to investigate the contribution of oxidative stress-regulated angiogenesis in the pathogenesis of bleomycin (BLM)-induced pulmonary fibrosis. In spite of a strong positive correlation between the angiogenic mediator vascular endothelial growth factor (VEGF) and pulmonary fibrosis, the role of VEGF in pulmonary fibrosis is poorly understood. Aim 1 is designed to establish the role of VEGF in the pathogenesis of pulmonary fibrosis and test the hypothesis that phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway regulates VEGF via hypoxia inducible factor (HIF)-11 in BLM-induced pulmonary fibrosis. Although pro-angiogenic environment is known to co-exist with progressive fibrosis, the contribution of neovascularization to the progression of fibrosis is understudied. The preliminary data demonstrates a significant increase in angiogenesis in vascular endothelial cells in response to BLM treatment. Aim 2 is designed to establish the involvement of angiogenesis in BLM-induced pulmonary fibrosis and test the hypothesis that angiogenesis during BLM-induced pulmonary fibrosis is dependent, in part, upon Akt mediated upregulation of the angiogenic mediator VEGF. Gene knockout and pharmacological approaches will be used to elucidate the role of Akt and identify its specific isoform(s) involved in the process. Increased oxidative stress have been implicated in lung injury and fibrosis and its inhibition has shown to offer significant protection against pulmonary fibrosis in animal models. Aim 3 is designed to evaluate if antioxidants such as manganese superoxide dismutase (MnSOD) mediate lung fibrosis by regulating the angiogenic (PI3K/Akt->HIF-1->VEGF) pathway. The preliminary data shows that Mn(III)tetrakis(4-benzoic acid) porphyrin (MnTBAP), an MnSOD mimetic, significantly blocked BLM-induced angiogenic and fibrogenic response. We hypothesize that MnTBAP might be effective in suppressing pulmonary fibrosis by modulating the angiogenic pathway. The proposed study will be important for the increased understanding of the molecular mechanisms involved in the pathogenesis of pulmonary fibrosis. The study will also aid in identifying key molecular targets, which may serve as novel biomarkers and provide alternative avenues for the development of potential therapeutic and preventive strategies for this fatal disease.